Encapsulation substrate for an organic light emitting diode display device

ABSTRACT

An organic light emitting diode (OLED) display device and method of fabrication that includes a substrate having a device region, an outer dam region and an encapsulation region. The encapsulation region includes an inner dam region, an outer dam region and an encapsulation region that correspond to the device region. An encapsulation agent is formed in the encapsulation region of the encapsulation substrate, and filling dams are formed of the same material in the outer dam region and the inner dam region of the encapsulation substrate.

CLAIM OF PRIORITY

This application claims the benefit of Korean Patent Application No.10-2009-0072805, filed on Aug. 7, 2009, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field if the Invention

An aspect of the present invention relates to an encapsulationsubstrate, an organic light emitting diode (OLED) display device havingthe same, and a method of fabricating the same.

2. Description of the Related Art

In recent times, flat panel display devices such as liquid crystaldisplay (LCD) devices, organic light emitting diode (OLED) displaydevices and plasma display panels (PDPs), which can overcomedisadvantages of conventional display devices such as cathode ray tubes,have attracted attention.

The LCD devices are light-receiving devices, not self-emitting devices,so that they have limitations in brightness, contrast, a viewing angleand a large-sized screen, and the PDPs are self-emitting devices, butthey are heavy, have high power consumption, and use a complicatedfabrication method in comparison with other flat panel display devices.

On the other hand, the OLED display devices are self-emitting devices,so that they have a wide viewing angle, high contrast and low powerconsumption, and are lightweight and thin because they do not need abacklight. Moreover, the OELD display devices are capable of beingdriven at a direct current low voltage with high response time, strongto external impact since they are solid, used in wide range oftemperature, and fabricated by a simple and inexpensive process.

However, organic thin films formed of organic compounds having lowthermal resistance are very vulnerable to moisture, and a negativeelectrode formed on the organic thin films is degraded in performancedue to oxidation. Thus, the organic thin films should be encapsulated toprevent invasion of moisture or oxygen.

The above information disclosed in this Related Art section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

Aspects of the present invention provide an organic light emitting diode(OLED) display device and a method of fabricating the same, which iscapable of enhancing the mechanical strength of a glass frit.

Aspects of the present invention also provide an OLED display device anda method of fabricating the same, which is capable of enhancing themechanical strength of a glass frit and providing a simple fabricationprocess.

According to an aspect of the present invention, an encapsulationsubstrate, includes: an encapsulation region in which an encapsulationagent is formed; an outer dam region formed within the encapsulationregion; and an inner dam region formed within the outer dam region.Here, filling dams are formed of the same material in the outer damregion and the inner dam region.

According to another aspect of the present invention, an OLED displaydevice, includes: a substrate including a device region, an outer damregion and an encapsulation region; and an encapsulation regionincluding an inner dam region, an outer dam region and an encapsulationregion to correspond to the device region, the outer dam region and theencapsulation region of the substrate, respectively. Here, anencapsulation agent is formed in the encapsulation region of theencapsulation substrate, and filling dams are formed of the samematerial in the outer dam region and the inner dam region of theencapsulation substrate.

The encapsulation agent may be a glass frit, which may be formed of oneselected from the group consisting of lead oxide (PbO), diboron trioxide(B₂O₈), and silicon dioxide (SiO₂).

A gap may be defined between the outer dam region and the encapsulationregion.

According to still another aspect of the present invention, a method offorming an encapsulation substrate, includes: providing an encapsulationsubstrate including an inner dam region, an outer dam region and anencapsulation region; applying an encapsulation agent to theencapsulation region; and forming an inner dam and an outer dam in theinner dam region and the outer dam region of the encapsulationsubstrate, respectively. Here, the outer dam is formed along an edge ofthe encapsulation substrate, and includes a discontinuous openingregion.

According to yet another aspect of the present invention, a method offabricating an OLED display device, includes: providing a substrateincluding a device region, an outer dam region, and an encapsulationregion; providing an encapsulation substrate including an inner damregion, an outer dam region and an encapsulation region to correspond tothe device region, the outer dam region and the encapsulation region ofthe substrate, respectively; applying an encapsulation agent to theencapsulation region of the encapsulation substrate; and forming aninner dam and an outer dam in the inner dam region and the outer damregion of the encapsulation substrate, respectively. Here, the outer damis formed along an edge of the encapsulation substrate, and includes adiscontinuous opening region.

The encapsulation agent may be a glass frit, which may be formed of oneselected from the group consisting of lead oxide (PbO), diboron trioxide(B₂O₈), and silicon dioxide (SiO₂).

The inner dam and the outer dam may have a viscosity of 30000 to 1000000cp.

The inner dam may include a linear inner dam and an oblique inner dam.

The inner dam may continuously extend from the outer dam.

The inner dam may be separated from the outer dam except for a region inwhich the inner dam continuously extends from the outer dam.

A gap may be defined between the outer dam region and the encapsulationregion.

The method of fabricating the OLED display device may further includealigning the device region, the outer dam region and the encapsulationregion of the substrate with the inner dam region, the outer dam regionand the encapsulation region of the encapsulation region to correspondto each other, and combining the substrate with the encapsulationsubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a cross-sectional view of a conventional organic lightemitting diode (OLED) display device;

FIG. 2 is a schematic plan view of an encapsulation substrate having atypical structure;

FIG. 3 is a schematic plan view of an encapsulation substrate accordingto the present invention;

FIGS. 4 through 6 illustrate a method of fabricating an OLED displaydevice according to the present invention in which FIG. 5B is across-sectional view of FIG. 5A along line I-I, and FIG. 5B is across-sectional view of FIG. 5A along line II-II; and

FIG. 7 is a schematic plan view illustrating another configuration of anencapsulation substrate according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the principles for thepresent invention.

Recognizing that sizes and thicknesses of constituent members shown inthe accompanying drawings are arbitrarily given for better understandingand ease of description, the present invention is not limited to theillustrated sizes and thicknesses.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. Alternatively, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

In order to clarify the present invention, elements extrinsic to thedescription are omitted from the details of this description, and likereference numerals refer to like elements throughout the specification.

In several exemplary embodiments, constituent elements having the sameconfiguration are representatively described in a first exemplaryembodiment by using the same reference numeral and only constituentelements other than the constituent elements described in the firstexemplary embodiment will be described in other embodiments.

FIG. 1 is a cross-sectional view of a conventional OLED display device.

Referring to FIG. 1, a substrate 10 is provided, and an OLED 20 isformed on the substrate 10. The OLED 20 includes a first electrode, anorganic layer having at least an emission layer, and a second electrode.

A thin film transistor including a semiconductor layer, a gate electrodeand source and drain electrodes may be further included.

Subsequently, an encapsulation substrate 40 is provided, a glass frit 30is formed on one surface of the substrate 10 or encapsulation substrate40 to combine.

Afterwards, laser is applied to the glass frit 30 to melt and solidify,and thus the conventional OLED display device is completed.

However, the glass frit has an excellent characteristic against theinvasion of moisture or oxygen, but has very weak mechanical strength.

FIG. 2 is a schematic plan view of an encapsulation substrate having atypical structure.

Referring to FIG. 2, the encapsulation substrate having a typicalstructure includes an encapsulation agent 110 formed on an encapsulationsubstrate 100, a dam 120 surrounded by the encapsulation agent 110, andan internal filling agent 130 surrounded by the dam.

Here, the encapsulation agent 110 is provided to seal a devicesubstrate, on which an organic light emitting diode (OLED) is formed,and the encapsulation substrate 100. The internal filling agent 130 isprovided to prevent an OLED display device from being damaged byexternal impact or pressure, and the dam 120 serves as a wall supportingthe internal filling agent during the formation of the internal fillingagent.

However, in the encapsulation substrate having the typical structure,the dam 120 and the internal filling agent 130 are formed of differentmaterials, so that the dam 120 and the internal filling agent 130 shouldbe formed in different processes. Thus, the fabrication process can becomplicated.

FIG. 3 is a schematic plan view of an encapsulation substrate accordingto the present invention.

Referring to FIG. 3, the encapsulation substrate according to thepresent invention includes an encapsulation agent 280 formed on anencapsulation substrate 260, and a filling dam 270 surrounded by theencapsulation agent 280. A gap 300 is also defined between the fillingdam and the encapsulation agent.

Here, the encapsulation agent 280 is provided to seal a devicesubstrate, on which an OLED is formed, and the encapsulation substrate260. The filling dam 270 is provided to prevent an OLED display devicefrom being damaged by external impact or pressure.

Unlike the encapsulation substrate having the typical structure, theencapsulation substrate according to the present invention is configuredso that the internal filling agent serving to prevent the OLED displaydevice from being damaged by the external impact or pressure isintegrated with a dam serving as a wall supporting the internal fillingagent, thereby forming the filling dam.

The configuration of the encapsulation substrate according to thepresent invention will be described with reference to a method offabricating an OLED display device according to the present invention inmore detail below.

FIGS. 4 through 6 are cross-sectional views illustrating a method offabricating an OLED display device according to the present invention.

To begin with, referring to FIG. 4, an OLED display device according tothe present invention provides a substrate 200, which includes a deviceregion 330, an outer dam region 310, and an encapsulation region 320.Here, a gap 300 is defined between the outer dam region 310 and theencapsulation region 320.

The substrate 200 may be an insulating substrate formed of glass orplastic, or a conductive substrate.

Subsequently, an OLED 210 is formed on the device region 330 of thesubstrate 200. The OLED 210 includes a first electrode 220, an organiclayer 230 having at least one emission layer, and a second electrode240.

In the OLED 210, the first electrode 220 may be a reflective electrode.The reflective electrode may be formed by sequentially stacking areflective layer and a transparent electrode. The reflective layer isformed of one selected from the group consisting of Ag, Mg, Al, Pt, Pd,Au, Ni, Nd, Ir, Cr and compounds thereof, and the transparent electrodeis formed of one selected from the group consisting of indium tin oxide(ITO), indium zinc oxide (IZO), tin oxide (TO) and zinc oxide (ZnO).

The first electrode 220 may also be formed in a stacked structure of alower electrode layer, a reflective electrode layer and an upperelectrode layer.

The lower electrode layer may be formed of one selected from the groupconsisting of ITO, IZO, TO and ZnO. Here, the lower electrode layer isformed to a thickness of 50 to 100 Å. When the thickness of the lowerelectrode layer is less than 50 Å, it is difficult to ensure uniformity,and when the thickness of the lower electrode layer is more than 100 Å,an adhesive strength is reduced due to stress of the lower electrodelayer.

The reflective electrode layer may be formed of one selected from thegroup consisting of Al, an Al alloy, Ag and an Ag alloy. Here, thereflective electrode layer may be formed to a thickness of 900 to 2000Å. When the thickness of the reflective electrode layer is less than 900Å, light is partially transmitted, and the thickness of about 1000 Å isthe minimum thickness that is not capable of transmitting light. Inaddition, when the thickness of the reflective electrode layer is morethan 2000 Å, it is not preferable in terms of production cost and time.

Here, the reflective electrode layer may reflect light to increasebrightness and luminous efficiency.

The upper electrode layer may be formed of one selected from the groupconsisting of ITO, IZO, TO and ZnO. Here, the upper electrode layer isformed to a thickness of 50 to 100 Å. When the thickness of the upperelectrode layer is less than 50 Å, it is difficult to ensure uniformityof a thin film. When the thickness of the upper electrode layer is morethan 100 Å, reflectance is reduced by at least 10 to 15%, particularlyin a blue region, due to interference.

The OLED of the present invention is a top-emission type. If the firstelectrode can be used for the top-emissive OLED, the material andstacked structure of the first electrode are not limited.

The organic layer 230 includes at least an emission layer, and may alsoinclude at least one of a hole injection layer, a hole transport layer,an electron transport layer and an electrode injection layer. In thepresent invention, the configuration and material of the organic layerare not limited.

As a material for the hole transport layer,N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (α-NPB) orN,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(TPD) may be used. The hole transport layer may be formed to a thicknessof 10 to 50 nm. When the thickness of the hole transport layer exceedsthe range, a hole injection characteristic is degraded, which is notpreferable.

In addition to the material for the hole transport layer, a dopantcapable of emitting light by electron-hole combination may be added tothe hole transport layer. As such a dopant,4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB), coumarin 6, rubrene, DCM, perylene or quinacridone may be used,and its content may be 0.1 to 5 wt % of the total weight of the materialfor the hole transport layer. When the dopant is added during theformation of the hole transport layer, the color of emitted light can becontrolled according to the kind and content of the dopant, and thusthermal stability of the hole transport layer is improved and a lifespan of the device increases.

The hole injection layer may be formed of a starburst amine-basedcompound to have a thickness of 30 to 100 nm. When the thickness of thehole injection layer exceeds the range, the hole injectioncharacteristic is degraded, which is not preferable. The contactresistance between a counter electrode and the hole transport layer maybe reduced due to the hole injection layer, and the hole transportingability of an anode electrode may be improved, so that thecharacteristics of the device are improved in general.

A material for the emission layer of the present invention is notparticularly limited, and may be 4,4′-bis(carbazol-9-yl)-biphenyl (CBP).

The emission layer of the present invention may further include a dopantcapable of emitting light by the electron-hole combination, like thehole transport layer described above, and the kind and content of thedopant are almost the same as those of the hole transport layer. Here,the emission layer may be formed to a thickness of 10 to 40 nm.

As a material for the electron transport layer,tris(8-quinolinolate)-aluminum (Alq3) or Almq3 may be used, and theelectron transport layer may further include a dopant capable ofemitting light by the electron-hole combination, like the hole transportlayer described above. Here, the kind and content of the dopant may bealmost the same as those of the hole transport layer, and the electrontransport layer may be formed to a thickness of 30 to 100 nm. When thethickness of the electron transport layer exceeds the range, efficiencyis reduced and a driving voltage increases, which are not preferable.

A hole blocking layer may be further formed between the emission layerand the electron transport layer. Here, the hole blocking layer mayprevent the transport of an exciton, which is formed from aphosphorescent light emitting material, to the electron transport layer,or prevent the transport of a hole to the electron transport layer. As amaterial for the hole blocking layer, Balq may be used.

The electron injection layer may be formed of a material including LiF,and formed to a thickness of 0.1 to 10 nm. When the thickness of theelectron injection layer exceeds the range, the driving voltageincreases, which is not preferable.

The second electrode 240 formed on the organic layer is formed in asemi-transmissive cathode type, or in a structure in which atransmissive cathode type is stacked on a semi-transmissive cathode. Thesemi-transmissive cathode type second electrode may be thinly formed toa thickness of 5 to 30 nm using one selected from the group consistingof Li, Ca, LiF/Ca, LiF/Al, Al, Mg and an Mg alloy. The second electrodehaving the stacked structure of the transmissive cathode type on thesemi-transmissive cathode may be formed by sequentially forming asemi-transmissive type cathode using one selected from the groupconsisting of metals having small work functions such as Li, Ca, LiF/Ca,LiF/Al, Al, Mg and an Mg alloy, and a layer using ITO or indium zincoxide (IZO), which has a low resistance characteristic. Here, when thethickness of the semi-transmissive cathode is less than 5 nm, anelectron is not injected at a low voltage, and when the thickness of thesemi-transmissive cathode is more than 30 nm, transmittance issignificantly reduced. It is preferable that the total thickness of thesemi-transmissive cathode and the transmissive cathode is 10 to 400 nm.

The OLED of the present invention is a top-emission type. If the secondelectrode can be used for the top-emissive OLED, the material andstacked structure of the second electrode are not limited.

Not shown in the drawings, the OLED 210 may further include a thin filmtransistor including a semiconductor layer, a gate electrode, and sourceand drain electrodes.

The thin film transistor may be formed in a top-gate structure in whicha gate electrode is formed on a semiconductor layer, or in a bottom-gatestructure in which a gate electrode is formed under a semiconductorlayer.

Subsequently, a protective layer 250 surrounding the OLED 210 is formed.

The protective layer 250 may be formed of an organic layer, an inorganiclayer, or a multiple layer thereof. The inorganic layer may be aninsulating layer formed of silicon oxide (SiO₂), silicon nitride(SiN_(x)), or silicon oxynitride (SiO_(x)N_(y)), or a LiF layer.Meanwhile, the organic layer may be a layer containingN,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)benzidine) (NPB), TNATA,TCTA, TDAPB, TDATA, Alq3, Balq or CBP.

The protective layer 250 may be formed by evaporation, CVD, orsputtering. The protective layer 250 may protect the organic layer fromexternal moisture or oxygen to prevent deterioration of the device.

Here, when the protective layer is formed of an inorganic layer, it maybe formed by sputtering, and when the protective layer is formed of anorganic layer, it may be formed by evaporation or CVD.

However, when the protective layer is formed by sputtering, the OLED maybe damaged. Thus, it is preferable that the protective layer is formedby evaporation or CVD, which causes less damage to the OLED. Therefore,it is preferable that the protective layer is formed of an organiclayer.

Since the OLED according to the present invention is a top-emissiontype, the protective layer may be transparent.

Next, a method of forming an encapsulation substrate according to thepresent invention will be described with reference to FIGS. 5A through5C. FIG. 5A is a schematic plan view of an encapsulation substrateaccording to the present invention, FIG. 5B is a cross-sectional viewtaken along line I-I′ of FIG. 5A, and FIG. 5C is a cross-sectional viewtaken along line II-II′ of FIG. 5A.

Referring to FIGS. 5A through 5C, an encapsulation substrate 260including an inner dam region 330, an outer dam region 310, and anencapsulation region 320 is provided to correspond to the substrate 200including the device region 330, the outer dam region 310 and theencapsulation region 320, described above. A gap 300 is also definedbetween the outer dam region 310 and the encapsulation region 320 of theencapsulation substrate, corresponding to the substrate.

The method of forming the encapsulation substrate will be describedspecifically below.

First, an encapsulation agent is applied to the encapsulation region 320formed along an edge of the encapsulation substrate 260.

The encapsulation substrate 260 may be formed of an insulating materialsuch as glass or plastic. The encapsulation agent may be a glass frit280, which is formed by melting one selected from the group consistingof lead oxide (PbO), diboron trioxide (B₂O₈) and silicon dioxide (SiO₂)to make glass, and grinding the glass into powder. Here, the glass frit280 may be applied by screen printing or dispensing.

The encapsulation agent is provided to seal the device substrate 200, onwhich an OLED is formed, and the encapsulation substrate 260. In thepresent invention, as the glass frit is used as the encapsulation agentto encapsulate the encapsulation substrate with the substrate, theinvasion of external moisture or oxygen may be effectively prevented.

Afterwards, a filling dam 270 is formed a predetermined distance of gap300 apart from the encapsulation agent applied to the encapsulationregion 320.

The filling dam 270 is formed within the encapsulation agent, andincludes an outer dam 270 a formed along the edge of the encapsulationsubstrate, and inner dams 270 b and 270 c formed within the outer dam270 a formed along the edge of the encapsulation substrate.

The inner dams 270 b and 270 c and the outer dam 270 a are disposed inan inner dam region 330 and an outer dam region 310 of the encapsulationsubstrate, respectively, and may be formed by screen printing ordispensing.

Here, the filling dam 270 may be formed of an UV- or heat-curingmaterial such as a silicon-based resin, an epoxy-based resin, anacryl-based resin or a polyimide-based resin, but in the presentinvention, the material of the filling dam is not limited thereto.

The filling dam according to the present invention may have a viscosityof 30000 to 1000000 cp. Here, the OLED according to the presentinvention is a top-emission type, so that the material of the fillingdam may be transparent.

The inner dams 270 b and 270 c are formed between the encapsulationsubstrate and the substrate to enhance mechanical strength of the glassfrit.

The glass frit has an excellent characteristic against the invasion ofmoisture or oxygen, but has very weak mechanical strength. Thus, toreinforce the strength of the glass fit, the inner dams are formedbetween the encapsulation substrate and the substrate to serve asinternal filling agents, thereby preventing the glass fit from beingdamaged by external impact or pressure, and also preventing the damageto the OLED display device.

Further, the outer dam 270 a serves as a wall supporting the inner dams270 b and 270 c.

To be specific, according to a subsequent process, the inner dams 270 band 270 c spread all over an inner side of the outer dam to serve asinternal filling agents. If the outer dam 270 a serving as a wall doesnot exist, the inner dam spreads up to the region in which the glassfrit is formed, to be in contact with the glass frit, resulting indegradation in adhesive strength of the glass frit. To prevent this, theouter dam 270 a is needed.

Meanwhile, the gap 300 is defined between the outer dam region 310 andthe encapsulation region 320 to prevent degradation of the adhesivestrength of the glass fit generated by contacting the spreading outerdam and the glass frit.

Here, as can be seen from outer dam gap region 340 of FIG. 5A, the outerdam 270 a includes a discontinuous opening region, which is notcontinuously formed along the edge of the encapsulation substrate.

As can be seen from FIG. 5A, the inner dam includes a linear inner dam270 b and an oblique inner dam 270 c, and as can be seen from outer damgap region 340 of FIG. 5A, the inner dam continuously extends from theouter dam 270 a.

The inner dams 270 b and 270 c are separated from the outer dam 270 aexcept for a region in which the inner dam continuously extends from theouter dam 270 a.

As described above, the encapsulation substrate 260 including the innerdam region 330, the outer dam region 310 and the encapsulation region320 is formed to correspond to the substrate 200 including the deviceregion 330, the outer dam region 310 and the encapsulation region 320.That is, the device region 330 of the substrate is formed to correspondto the inner dam region 330 of the encapsulation substrate.

The characteristics described above will be described in further detailwith reference to a following process.

Referring to FIG. 6, the encapsulation substrate 260 formed as describedabove is aligned with the substrate 200 formed as described above tocombine.

That is, the device region 330, the outer dam region 310 and theencapsulation region 320 of the substrate 200 are aligned with the innerdam region 330, the outer dam region 310 and the encapsulation region320 of the encapsulation substrate 260 to correspond to each other, andthe both substrates 200 and 260 are combined with each other.

Here, the device region 330 of the substrate is aligned with the innerdam region 270 b of the encapsulation substrate to correspond to eachother.

The inner dams 270 b and 270 c spread all over the inner side of theouter dam due to the combination of the substrate with the encapsulationsubstrate, and thus serve as internal filling agents.

Here, as described above, the outer dam 270 a includes the openingregion, which is not continuously formed along the edge of theencapsulation substrate. The inner dams are separated from the outer dam270 a except for the region in which the inner dam continuously extendsfrom the outer dam 270 a.

According to the present invention, since air or bubbles are present ina predetermined space defined between the inner dams, the outer dam andthe inner dams are formed to provide a path for exhausting the air orbubbles during the process of combining the substrate with theencapsulation substrate.

To this end, when the substrate is combined with the encapsulationsubstrate, the inner dams fill the predetermined space therebetween andspread all over the inner side of the outer dam. Here, to exhaust theair or bubbles present in the predetermined space, the opening region isformed in the outer dam.

In addition, the inner dams are separated from the outer dam not to trapthe air or bubbles in the space defined by contact between the outer damand the inner dam.

Here, the air or bubbles exhausted through the opening region of theouter dam may be exhausted outside through the encapsulation agent. Upto the present process, the encapsulation agent, the glass fit, was notcured, so that the air or bubbles can be exhausted outside through theencapsulation agent.

In the present invention, the outer dam and the inner dams arecontinuously formed only by once process.

On the other hand, FIG. 7 is a schematic plan view illustrating anotherconfiguration of an encapsulation substrate according to the presentinvention. As can be seen from outer and inner dam gap region 360 ofFIG. 7, an outer dam and inner dams may be separated from each otherwithout a region in which the inner dam continuously extends from theouter dam.

According to the present invention, the inner dam includes a linearinner dam 270 b and an oblique inner dam 270 c.

During the formation of the inner dam, as shown in inner dam connectionregion 350 of FIG. 5A, materials for the inner dams are concentrated ina certain region, in which ends of the inner dams are in contact witheach other, thereby trapping air or bubbles. To prevent this, in thepresent invention, it is preferable that the oblique inner dam isformed.

For example, as can be seen from FIG. 5B, the number of the inner damsare nine. If all of the inner dams, not just some, are formed in alinear type, a distance between ends of the inner dams becomes smallerthan the case that some of the inner dams are formed in an oblique typein the same space. Thus, when the substrate is combined with theencapsulation substrate, the ends of the inner dams are in contact witheach other first, thereby trapping the air or bubbles.

Therefore, the distance between the ends of the inner dams can becomegreater by forming some of the inner dams in an oblique type. Thus, itis preferable that the inner dam according to the present inventionincludes the linear inner dam 270 b and the oblique inner dam 270 c.

As described above, the filling dam according to the present inventionmay have a viscosity of 30000 to 1000000 cp. When the viscosity of thefilling dam is less than 30000 cp, liquidity of the filling damincreases due to the very low viscosity, and thus the inner dams can bein contact with each other, or the inner dam is in contact with theouter dam, thereby trapping the air or bubbles.

During the process of combining the substrate with the encapsulationsubstrate, the inner dams fill the predetermined space therebetween, andspread all over the inner side of the outer dam. Here, when theviscosity of the filling dam is more than 1000000 cp, due to very highviscosity, the liquidity of the filling dam decreases, and thus it isdifficult that the inner dams spread all over the inner side of theouter dam.

Meanwhile, the device region 330 of the substrate is aligned with theinner dam region 330 of the encapsulation substrate to correspond toeach other. This is for only an inner dam formed in the inner dam regionof the encapsulation substrate to be pressed by a device formed on thedevice region of the substrate in order to spread all over the innerside of the outer dam.

This is because if the device region of the substrate is formed up tothe outer dam region of the encapsulation substrate, beyond the innerdam region of the encapsulation substrate, the outer dam in the outerdam region of the encapsulation substrate is pressed out to theencapsulation agent by the device formed on the device region of thesubstrate, to be in contact with the encapsulation agent.

To solve this problem, as described above, in the present invention, itis preferable that the gap 300 is defined between the outer dam region310 and the encapsulation region 320, and thus the contact between theouter dam and the encapsulation agent can be prevented.

Subsequently, laser is applied to the glass frit 280 to melt andsolidify, and then heat or UV is applied to the filling dam to cure.Thus, an OLED display device according to the present invention iscompleted.

In the OLED display device completed as described above, theencapsulation substrate corresponds to the encapsulation substrate ofFIG. 3. As described above, unlike the encapsulation substrate formed inthe typical structure, the internal filling agent provided to preventthe OLED display device from being damaged by external impact orpressure may be formed using the same material and process as the damserving as a wall supporting the internal filling agent, which canprovide a simple fabrication process.

Consequently, the present invention provides an OLED display device anda method of fabricating the same, which has an excellent characteristicagainst invasion of moisture or oxygen by combining a substrate with anencapsulation substrate using a glass fit.

The present invention also provides an OLED display device and a methodof fabricating the same, which is capable of enhancing mechanicalstrength of the glass frit.

The present invention also provides an OLED display device and a methodof fabricating the same, which is capable of providing a simplefabrication process as well as enhancing mechanical strength of a glassfrit.

In the exemplary embodiments shown in FIG. 5A and FIG. 7 the linearinner dams 270 b and oblique inner dam 270 c are connected at inner damconnection region 350 and form a zigzag pattern in which the linearinner dams 270 b and the oblique inner dam 270 c are at an angle ofbetween 120° and 180°. However, the present invention is not limited tosuch a zigzag pattern.

Although the present invention has been described with reference topredetermined exemplary embodiments thereof, it will be understood bythose skilled in the art that a variety of modifications and variationsmay be made to the present invention without departing from the spiritor scope of the present invention defined in the appended claims andtheir equivalents.

What is claimed is:
 1. An encapsulation substrate, comprising: anencapsulation region in which an encapsulation agent is formed, theencapsulation agent being a glass frit; an outer dam region formedwithin the encapsulation region, said outer dam region having adiscontinuous opening region and a gap between the outer dam region andthe encapsulation region; an inner dam region formed within the outerdam region; and filling dams formed of the same material in the outerdam region and the inner dam region.
 2. The encapsulation substrateaccording to claim 1, wherein the glass frit is formed of one selectedfrom the group consisting of lead oxide (PbO), diboron trioxide (B₂O₈),and silicon dioxide (SiO₂).
 3. The encapsulation substrate according toclaim 1, wherein each of the filling dams is formed of an UV- orheat-curing material.
 4. An organic light emitting diode (OLED) displaydevice, comprising: a substrate including a device region, an outer damregion and an encapsulation region, the encapsulation region includingan inner dam region, the outer dam region, and the encapsulation regionencompassing the device region and the outer dam region of thesubstrate, respectively, said outer dam region having a discontinuousopening region and a gap between the outer dam region and theencapsulation region; an encapsulation agent formed in the encapsulationregion of the encapsulation substrate, said encapsulation agent being aglass frit; and filling dams formed of the same material in the outerdam region and the inner dam region of the encapsulation substrate. 5.The OLED display device according to claim 4, further comprising an OLEDformed on the device region of the substrate.
 6. The OLED display deviceaccording to claim 4, wherein the glass frit is formed of one selectedfrom the group consisting of lead oxide (PbO), diboron trioxide (B₂O₈),and silicon dioxide (Si0 ₂).
 7. The OLED display device according toclaim 4, wherein each of the filling dams is formed of a transparentmaterial.
 8. The OLED display device according to claim 4, wherein theOLED further includes a thin film transistor having a semiconductorlayer, a gate electrode, and source and drain electrodes.